Improving the ring-opening polymerization of ε-caprolactone and l-lactide using stannous octanoate

Abstract

A series of ligands were tested to meliorate the catalytic activity of e-caprolactone (CL) and L-lactide (LA) polymerization by Sn(Oct) 2 and BnOH. There are seven ligands (methyl 2-(dibenzylamino)acetate (MDBAA), di(1H-pyrazol-1-yl)methane, benzanide, 8-aminoquinoline, 2-bromo-1-phenylethanone, 2,6-di-tert-butyl-4-methylphenol, and dipyridine) were found to be useful in increasing the polymerization rate for CL polymerization. For LA polymerization, there are only two ligands (8-aminoquinoline and p-thiocresol) effectively raised the polymerization rate. Moreover, the kinetic study reveals a first-order dependency on [CL] and second-order dependency on [LA], indicating different polymerization mechanisms in Sn(Oct) 2 catalytic system. The mechanistic study also explains that MDBAA could potentially modify the framework of the catalytic intermediate and produce the hydrogen, thereby increasing the rate of CL polymerization.

Development of Amphotericin B Micellar Formulations Based on Copolymers of Poly(ethylene glycol) and Poly(ε-caprolactone) Conjugated with Retinol

“…The average molecular weights (Mn) are listed in Table 1. The dispersion indexes estimated by gel permeation chromatography coincide with values reported for polymerization catalysed by Sn(Oct) 2 [49]. Afterward, the resulting AB and ABA copolymers were reacted with succinic anhydride to obtain a carboxylate copolymer at the PCL ends.…”

Efficient Cellulose Dissolution and Film Formation Enabled by Superbase Amino Acid Ionic Liquids

“…This trend is the result of the combined effect of van der Waals force and hydrogen bonding. [ 26 ] An increase in carbon chain length in amino acids favors the enhancement of van der Waals force, leading to an increase in T g values. [ 25 ] Meanwhile, an increased number of carboxyl or hydroxyl groups on the side chains of amino acids promotes hydrogen bonding.…”

“…Kamlet–Taft parameters, including hydrogen bond acidity ( ɑ ), hydrogen bond basicity ( β ), and polarizability ( π * ), were determined using solvochromic dyes, namely NA, DENA, and RD. [ 26 ] UV absorption spectra of solvochromic dyes in the presence of SAAILs were recorded on a UV–vis spectrophotometer (UV1900, Japan). The corresponding parameters were calculated as follows: $$$$\begin{equation}{{\rm{{\rm N}}}_{{\rm{(dye)}}}} = 1/({{{\lambda}}_{{\rm{max(dye)}}}}{\rm{*1}}{{\rm{0}}^{{\rm{ - 4}}}}{\rm{)}}\end{equation}$$$$ $$$$\begin{equation}{\rm{ET}}\left( {{\rm{30}}} \right) = 28592/\lambda {\rm{max}}\left( {{\rm{RD}}} \right)\end{equation}$$$$ $$$$\begin{equation} \pi * = 0.314\left( {{\rm{27}}{\rm{.52}} - {{\nu}}\left( {{\rm{DENA}}} \right)} \right)\end{equation}$$$$ $$$$\begin{equation}\alpha = 0.0649{\rm{Et}}\left( {30} \right) - 2.03 - 0.72\pi *\end{equation}$$$$ $$$$\begin{equation} \beta = \left( {{\rm{1}}{\rm{.035\nu }}\left( {{\rm{NA}}} \right) + 2.64 - {{\nu}}\left( {{\rm{DENA}}} \right)} \right){\rm{/2}}{\rm{.80}}\end{equation}$$$$Where λ max(dye) is the wavelength corresponding to the maximum absorbance of solvochromic dye.…”

The Synthesis of Novel Gallium Carbenes, Nitrenes, Phosphinidenes and Alkoxides

“…As stated in chapter one, p-block alkoxides have been used for the polymerisation of lactic acid and glycolic acid, but also for ε-caprolactone, another biodegradable, renewable polymer. 63 The alkoxide ligands on the metal centre readily form hydrogen bonds with an alcohol used to initiate the ring opening metathesis polymerisation reaction. These hydrogen bonds help bind the polymer chain to the metal centre, and facilitate the nucleophilic attack on the monomer by the alcohol functionality.…”

“…Figure 28: Polymerisation of the L-lactic acid dimer by Sn(Oct) 2 . Figure redrawn from Chen et al63 …”